This disclosure generally relates, in various exemplary embodiments, to polycarbonate compositions and articles formed from such compositions having enhanced low-temperature ductility, UV resistance and/or fire-retardance characteristics, as well as uses thereof.
With their strength and clarity, polycarbonate (PC) and copolycarbonate resins offer many significant advantages and are utilized for a number of different commercial applications. Polycarbonate materials are playing a vital role today in applications including electronic engineering (E&E) parts, mechanical parts and so on. Unfortunately, the ductility of polycarbonate resins is adversely affected with sharp notches, high strain rate, and low temperature. To overcome this problem, impact modifiers such as methyl methacrylate/butadiene/styrene copolymer (MBS), poly butylarylate (BA), and polysiloxane have been blended with polycarbonate. For example, U.S. Patent Application Publication No. 2004/0249070 to Lim et al. discloses a polycarbonate composition comprising a rubber modified vinyl-grafted copolymer, a phosphorous mixture of a cyclic phosphazene oligomer compound and a phosphoric acid ester as a flame retardant, and a fluorinated polyolefin resin. In the application, examples of the rubber modified vinyl-grafted copolymer include acrylonitrile-butadiene-styrene (ABS) resin and MBS resin.
U.S. Pat. No. 6,914,090 to Seidel et al. discloses an impact-resistant and flameproofed polycarbonate molding composition suitable for making thin-wall housing parts. The composition contains 5 percent to 20 percent by weight of rubber-modified vinyl(co)polymer, 2 percent to 15 percent by weight of at least one low-volatility, halogen-free flameproofing agent, and 0.1 percent to 6 percent by weight of a silicate mineral. The rubber content of the composition is 2 percent to 6 percent by weight based upon the total weight of the composition.
U.S. Pat. No. 6,063,844 to Barren et al. discloses a thermoplastic resin composition comprising an aromatic polycarbonate resin and a rubber modified graft copolymer. The rubber modified graft copolymer comprises a discontinuous elastomeric phase dispersed in a continuous rigid thermoplastic phase, and at least a portion of the rigid thermoplastic phase being chemically grafted to the elastomeric phase.
U.S. Patent Application Publication No. 2003/0105226 to Cella discloses a polysiloxane-modified polycarbonate comprising polysiloxane units and polycarbonate units. The polysiloxane segments comprise 1 to 20 polysiloxane units. Uses of other polysiloxane-modified polycarbonates are described in U.S. Pat. No. 5,380,795 to Gosen, U.S. Pat. No. 4,756,701 to Kress et al., U.S. Pat. No. 6,657,018, U.S. Pat. No. 5,488,086 to Umeda et al., and EP 0 692 522B1 to Nodera, et al., for example.
However, the introduction of rubber or polysiloxane to polycarbonate materials has some disadvantages. For example, neither polybutylarylate nor polysiloxane has the low-temperature impact compensation capability for the polycarbonate matrix. Core-shell type rubbers such as MBS, cause the polycarbonate matrix to exhibit poor thermal stability and weatherability due to the existence of unsaturated double bonds They also produce poor light resistance and unsatisfactory fire-retardance characteristics. As such, formulations with MBS as an impact modifier are not very desirable for high temperature molding and outdoor applications.
There accordingly remains a need in the art for polycarbonate compositions that can readily produce an article with enhanced low-temperature ductility, UV resistance and/or fire-retardance characteristics, among other properties.